ADU Construction Cost in San Bernardino County (2026): City-by-City Breakdown
A adu construction in San Bernardino County costs $255–$425 per sq ft, with a typical mid-size ADU running $77k–$153k at the county average. Small projects start around $51k; large or high-end work can reach $383k or more.
San Bernardino County runs about 15% below the LA County baseline due to Inland Empire labor rates and shorter permit queues that run well below the coastal SoCal average.
ADU Construction Cost by Size — SB County Average
County-average ranges (0.85× LA County baseline). Individual cities vary — see the table below.
| Size | Type | Range | Low | High |
|---|---|---|---|---|
| Small | JADU / studio | 150–400 sq ft | $51k | $111k |
| Medium | 1-bed garage conversion | 400–600 sq ft | $77k | $153k |
| Large | Detached 2-bed | 800–1,200 sq ft | $213k | $383k |
ADU Construction Cost by City in San Bernardino County
Every city in San Bernardino County, sorted alphabetically. Totals reflect each city's local cost multiplier. Cities in color have full project-specific pages.
| City | Small | Medium | Large |
|---|---|---|---|
| Chino | $53k–$115k | $79k–$159k | $220k–$396k |
| Chino Hills | $57k–$124k | $86k–$171k | $238k–$428k |
| Colton | $49k–$107k | $74k–$148k | $205k–$369k |
| Fontana | $50k–$108k | $75k–$150k | $208k–$374k |
| Hesperia | $47k–$102k | $70k–$141k | $195k–$351k |
| Highland | $50k–$108k | $75k–$150k | $208k–$374k |
| Ontario | $51k–$111k | $77k–$153k | $213k–$383k |
| Rancho Cucamonga | $54k–$117k | $81k–$162k | $225k–$405k |
| Redlands | $53k–$115k | $79k–$159k | $220k–$396k |
| Rialto | $49k–$107k | $74k–$148k | $205k–$369k |
| San Bernardino | $50k–$108k | $75k–$150k | $208k–$374k |
| Upland | $54k–$117k | $81k–$162k | $225k–$405k |
| Victorville | $47k–$102k | $70k–$141k | $195k–$351k |
| Yucaipa | $51k–$111k | $77k–$153k | $213k–$383k |
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Get MatchedWhat Affects ADU Construction Cost in San Bernardino County?
- ADU type (JADU vs attached vs detached).
- Site prep and grading.
- Utility connections.
- CA Title 24 energy compliance.
- City ADU permit timeline.
- SB County market dynamics: Inland Empire labor rates and shorter permit queues that run well below the coastal SoCal average, which shifts adu construction totals about 15% below the LA County baseline.
- City variation within SB County: coastal and hillside cities can run 15–30% above the county mid-point, while inland labor markets price 10–20% below.
ADU Construction Sub-Type Comparisons
Garage Conversion ADU vs Detached ADU
Garage conversions reuse the existing slab and shell; a detached new-build ADU costs more but unlocks larger floor plans and higher rent.
Junior ADU (JADU) vs Attached ADU
A JADU (≤500 sq ft, within the home) shares utilities; an attached ADU is a true second unit with its own entrance and meter.
How to Get the Best Price on a ADU Construction in San Bernardino County
- Get 3 line-itemized bids on the same scope through Keystone Connect — SB County adu construction pricing varies 10–25% between contractors.
- Compare bids from contractors based in multiple SB County cities; inland-based crews servicing coastal jobs often beat coastal-based pricing.
- Bid in shoulder seasons (Jan–Mar or Sep–Oct) when SB County contractor schedules are open and rush premiums disappear.
- Verify CSLB license, insurance, and bond before paying any deposit. California caps deposits at $1,000 or 10% of contract, whichever is less.
Frequently Asked Questions — ADU Construction in San Bernardino County
Keep exploring
Compare adu construction costs across San Bernardino County, or browse other projects and guides.
More SB County cost guides
ADU Construction by city
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